<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // let num=100;
        // let str="hello,world"
        // let nu=null
        // let und=true
        // console.log(typeof(und))
        //引用类型
        let arr=[1,2,4]
        let reg=/123/
        let date=new Date
        console.log(arr instanceof Array)
        console.log(reg instanceof Array)
        console.log(date instanceof Object)
    </script>
</body>
</html>